1. Field of the Invention
The present invention relates generally to film holders, and particularly to such holders that are mountable on a photographic camera back and cooperate with a compatible film assemblage to facilitate daylight-handling of one or more photosensitive film sheets in the assemblage.
2. Description of the Prior Art
The prior art is replete with film holders of the type referred to above. Examples may be found in the following documents.
U.S. Pat. No. 3,053,160--Discloses a film holder (12), mountable on a camera back, for holding in exposure position, and then initiating processing of, a self-processable film assemblage (68). The assemblage (68) is held in exposure position between a fixed rear plate (20) and a fixed front plate (18) having an exposure window. A slider (116) is manually actuable in a plane parallel with those plates (20, 18) to move assemblage-engaging latches (106 & 102, 104) perpendicularly away from the assemblage, to permit withdrawal of the assemblage, and is spring-returned (122, 128) when released to restore said latches (106 & 102, 104) to their assemblage-engaging positions. This film holder is similar to the Polaroid 545 Land Film Holder used by professional photographers.
U.S. Pat. No. 3,319,555--Discloses a film holder (10) having a pressure plate (21) that is actuated to move perpendicularly relative to the film plane by movement of a slider (11) parallel with said plane. The slider (11) has angled spring legs (31) thereon in slidable engagement with the pressure plate (21). The spring legs cause the pressure plate to move away from the film plane when the slider is pushed inwardly, and back toward said plane when the slider is released and spring-returned (17) to its initial, outward position.
U.S. Pat. No. 4,725,865--Discloses a film holder (47), usable in a camera back, comprising base and cover portions (26 & 33a) that are telescopically associated for relative movement toward and away from each other in directions perpendicular to the film plane. The base and cover portions are normally biased away from each other into an open position by springs (45) disposed therebetween. A rigid, planar film-supporting surface (27) is fixed inside the base portion in parallel relation to the top wall (38) of the cover portion, to define a film pathway (46) extending therebetween in alignment with an access slot (42) in an end wall (39) of the cover portion. When the holder is in its normally open position, a film assemblage (1a) can be freely inserted and withdrawn through the slot and along the pathway. With an assemblage fully inserted, the base and cover portions are urged toward each other (in opposition to the springs) into a closed position by the act of loading the holder into a spring-loaded camera back. When the holder is thus brought to its closed position, a tab (43) and a stop (43a), which depend from the cover portion top wall, are caused to protrude into the pathway so as to interact with a clip (8) and a stop-strip (14a) on the assemblage. To withdraw or reinsert an assemblage, the holder must first be removed from the camera back and thereby restored to its open position, wherein the tab and stop are both clear of the pathway.
U.S. Pat. No. 4,821,055--Discloses a holder (H), mountable on a camera back, for use with a cooperating packet (P) having film (F, F') removably attached to a carrier (C), which has, at one end (18), an asymmetrical tab (24) and, at its opposite end (20), a transverse light-locking element (30). Telescopically receivable over the carrier (C) and film (F, F') is a light-shielding envelope (E). The envelope (E) has an open end (46) that is closable by engagement with the light-locking element (30) and a closed end (44) with a squeezable area (62) that overlies and, when grasped, squeezes the tab (24), to prevent inadvertent separation of the envelope (E) from the carrier (C). An adjacent area (64), not overlying the tab (24), is graspable for pulling the squeezable area (62) free of the tab (24) and the envelope (E) away from the film (F, F'), to permit intended exposure. The envelope (E) also has, near its open end (46), a stop strip (66, 68) for limiting envelope (E) movement. The packet (P) is slidably insertable into, and withdrawable from, the holder (H), which comprises a spring-loaded (132) pressure-applying member (130) for maintaining the film (F, F') in an exposure plane, a spring-loaded (140) latching member (138) engageable with the light-locking element (30) to retain the carrier (C) in place, a spring-loaded (142b, c, d) stopping member (142a) engageable with the stop strip (66, 68) to limit envelope (E) movement while the carrier (C) is retained, and a spring-loaded releasing member (144) that is manually actuable (184) for negating (158, 168 & 166) the spring-loadings (132, 140 & 142b, c, d) on the pressure-applying, latching, and stopping members (130, 138 & 142a), to permit unrestricted withdrawal of the packet (P) from the holder (H). To withdraw the packet (P) from this holder (H), it is necessary to both actuate and then hold the spring-loaded releasing member (144) in its fully actuated position while the packet (P) is being withdrawn. Should the user let go of the releasing member (144) before the packet (P) has been completely withdrawn, the spring-loaded stopping member (142a) will intercept the exiting light-locking element (30) and may then tear that element (30) from its carrier (C) and/or become damaged by it. This holder (H) has thus posed a problem to users who fail to hold the releasing member (144) in its fully actuated position while they pull the packet (P) out of the holder.